Is it the intent of the code to allow a flapper/damper and
screen protection for a residential wall cap (mechanical
Ventilation)
Interpretation #7864
Published November 14, 2016
Original Request
- Code Version
- 2014
- Code
- MECHANIC
- Code Description
- Chapter
- 5
- Section
- 501.3.2
- Topic
Question
Answer Published 11/14/2016 at 9:03 AM
The answer is "PROBABLY." The request does not state whether
the exhaust is bathroom, kitchen, or clothes dryer. The
referenced section says nothing about flappers or dampers, It
addresses screens. Section 504.4 mandates a backdraft
damper and prohibits screens at the termination.
the exhaust is bathroom, kitchen, or clothes dryer. The
referenced section says nothing about flappers or dampers, It
addresses screens. Section 504.4 mandates a backdraft
damper and prohibits screens at the termination.
Commentary
While 501.3.2 refers to a commercial application,
residential occupancies not covered by the residential volume
fall within this category. If the issue relates to a One or
Two Family Dwelling, the wall cap duct termination would be
section M1506.2 of the residential code. This section then
sends you to 303.6 Outside Opening Protection: ... shall be
protected with screens louvers or grilles ...opening shall
be protected against local weather conditions... based on
this, the answer is yes if the flapper purpose is weather
protection for that residential application.
Note: No screen allowed in a dryer application